Manufacture of shoe stiffener material



scrap has been reduced to a uniform pulp suspension characterized by a smooth and more or less slimy feel. A beating period of about two hours may be all that is necessary to ensure a pulp suspension which can be formed into a sheet of uniform texture. The beaten pulp suspension having a consistency of, say, about 5%, is then transferred to a stuff chest wherein it is diluted under agitation with water to a consistency of, say, about 1t% to 1/ The dilute pulp suspension is then passed to a Wet machine and formed into a sheet which is wound on the make-up roll to the desired thickness and stripped in Wet condition therefrom. I have found it necessary to use a special fabric for removing the layer of pulp from the cylinder mould and transferring it to the make-up roll. Thus, when the usual transfer felt is used, the layer of pulp tends to stick to the felt rather than to the make-up roll. The use of napless toweling cloth or similar Woven fabric as the pulp carrier obviates the foregoing diiiculty. The wet sheet removed from the make-up roll is then dried, preferably under tension, since otherwise it tends to cockle or warp badly on account of the great shrinkage which takes place during drying. The dry sheet may then be ammoniated by dipping it into a solution made up of, say, equal parts of water and ammonia Water of 28% concentration. The sheet should be kept immersed for a period of at least about one hour to effect the desired action. The wet, ammoniated sheet is limp and in this condition can be easily cut into counter blanks and moulded into counters, or cut into box toe blanks which can be kept in moist condition and packaged and shipped in such condition to the shoe factory. 0n the other hand, the sheet may be cut up into shoe stiffener blanks, which are dry when they-reach the shoe factory, but which may 'be rendered soft and mouldable by soaking in water at :the shoe factory.

The ammoniation of the sheet can be performed, as already indicated, with ammonia fumes, in which case the sheet in moist condition as removed from the wet machine may be placed in a chamber filled with ammonia fumes which readily penetrate into and incipiently gelatinize the leather fibers to produce 'the desired product. When the moist, ammoniated sheet is subjected to a drying operation before cutting into shoe stifener parts, it is preferable to compact the sheet as y passing it between calender rolls before it 'is completely dried, as this enhances the density translucency and horn-like character o the product.

While I do not` know precisely what reaction takes place on the sheet of leather fibers when it is subjected in the presence of moisture to the action of ammonia, nevertheless? my picture is that the ammonia first the chrome tanning agent and then partially or incipiently glutinizes the detanned fibers. The partial glutinization is reflected in the dense, horny, and translucent qualities in the finished product. The detanning action is reflected in the ability of the product to absorb Water and become softened thereby. On drying, too, the water-softened product simulates untanned leather in its high shrinkie and warping and in its becoming horn- The procedure hereinbefore given may be departed from in certain respects, depending upon the particular scrap leather used, the characteristics desired in the ultimate product,I and the amounts of material being handled. Thus, where large-scale operation is practised, the time of beating may be much longer than the two-hour period hereinbefore mentioned, especially when a sheet of comparatively high density, even before ammoniation, is desired. Rather than forming a finished sheet composed entirely of leather, I may produce one which has a reinforcement or backing of fabric. For example, a fabric may be applied to the sheet before or after it is taken off the make-up roll of the cylinder machine, in which case the fabric adheres tenaciously t0 the sheet Without the use of extraneous cementing agents. Rather than forming the sheet on a cylinder machine, the sheet may be made on a F ourdrinier machine, in which case the ammoniation may be performed on a continuous sheet, either bedry end o the machine. Thus, the continuous Wet sheet formed on the wire may be- 4fore dryin or after the sheet is taken off the .f

that the aqueous suspension of leather fibers f may be de sited as a layer on a coarsely woven fabrlc, such as cheesecloth, thereby ob viating the step of a plying the fabric'to a preformed sheet of ers.

It is to be observed that performv the beating operation on tanned leather fibers and partlally or incipiently lutinize the leather fibers only after the ormation of the sheet.' By 'so doing, I avoid loss of ra'w material in the water drained from the papermaking machine, as little material is leached out of the tanned leather during the beating operation. Moreover the leather fibers can be maintained sumciently long to ,permit their interfelting on the apex' machine into a porous sheet of consi erable strength and tear 'excess is needed in reacting upon the highly dilute stock in the beater engine, but the glutinized material, being soluble in water, would be lost in considerable amount along with the Water removed during sheet formation.

The use of ammonia is of advantage, in that it is a volatile glutinizing agent and ef fects the desiredl partial or incipient glutinizing action on the sheet, without tending to disintegrate it. During drying, substantially all of the ammonia is removed, so that the sheet is free from malodors or adulterants Which detract from its translucency and horn-like character.

In producing the product of the present invention, it is essential to use only fibrous materialv upon which ammonia. can react. Were cellulose fiber incorporated in substantial amount into the leather furnish, one could not secure a product having the characteris-v tics hereinbefore noted, for cellulose fibers are practically inert -With respect to ammonia,

and would tend to render'the product opaque,

as well as to detract from its density, resiliency, and horn-like qualities. When cellulose yfiber is used in substantial amount, the

product, even Vafter ammoniation', is paperlike in its characteristics. On the other hand, one may use yanimal fibers, such as goats o'r cows hair, along with the leather, as such fibers are partially glutinized along with the leather during the ammoniating treatment. The product may bemodified somewhat by the use of various agents. Thus, it may be hardened by impregnation with an aqueous solution of sodium silicate, and then drying.

It may be permanently softened somewhat by treatment with an aqueous solution of glycerin or so-called fat liquors, e. g., sulphonated castoreoil. These treatments may be performed while preserving such qualities as translucency, density, and resiliencyi in ing in `Water and to be set in moulded shape.

3. A method which com rises beating animal fiber in the presence o water to produce a uniform aqueous pulp suspension, sheeting the pulp, and ammoniating the sheeted pulp in the presence of water to eEect partial glutinization of the fiber.

4. A method which comprises beating ani'- mal fiber in the presence of Water to produce a uniform aqueous pulp suspension, sheeting the pulp, ammoniating the sheeted pulp in the presence of Water to eect a partial glutinization of the fiber, and compacting the partially glutinized sheet.

' 5. A method which com-prises beating chrome-tanned leather scrap in the presence of Water to produce a uniform aqueous pulp suspension, sheeting the pulp, and ammoniating the sheeted pulp in the presence of Water to effect partial glutinization of the leather fibers.

6. A process which comprises beating in water chrome-tanned leather scrap in substantially the same Wet condition as itl is derived from hides Wet with the tanning-.liquor to produce a uniform aqueous pulp suspension, sheeting the pulp, ammoniating the sheeted pulp in the presence of water to effect partial glutinization of the leather fiber, and

cutting the partially glutinized sheet into shoe stiffener parts.

' 7. A method which comprises reducing animal fiber in the presence of water to a uniform pulp, sheeting the pulp, partially glutinizing the fibers in situ in said sheet 1n signature. y

FRANK O. WOODRUFF.

the product, land Without deleteriously af-V fecting the ability of the product to be rendered soft a-nd mouldable by mere soaking in Water.

' 1. Shoe stifener material comprising a partially glutinized, Prefabricated sheet of water-laid, interfelted animal fibers, said sheet being characterized by its translucency, density, resiliency, and ability to be rendered limp and mouldable by soaking in Water and to be set in moulded shape.

2. Shoe stiffener material comprising an ammonia-glutinized, prefabricated Waterlaid sheetof beaten, chrome-tanneddeathcr scrap, said sheet being characterized by its translucency, density, resiliency, and ability to be rendered limp and mouldable by soak- 

